Cleaning stack gas

ABSTRACT

A method and apparatus for cleaning and recycling stack gas from coal-fired power plants, from natural or propane burning heating plants, or from cement kilns by using renewable catalysts of zeolite to separate pollutants into recyclable and reusable materials. The method reduces from the stack gas carbon monoxide (CO), carbon dioxide (CO 2 ), nitrogen oxide (NOx), sulfur oxide (SOx) as well as halogens such as chloride and fluorides and trace metals particularly, mercury, lead, and zinc. Bauxite compounds can also be separately collected if desired. The method and apparatus also result in production of fertilizer products by purging with gaseous or liquid nitrogen the zeolite beds through which the stack gas flows. The oxygen split in the beds may be recycled to the burners in the plant.

RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 13/841,339, filed Mar. 15, 2013.

BACKGROUND AND SUMMARY

This invention relates to cleaning of stack gases such as those fromcoal fired power plants, from natural or propane burning heating plants,or from cement kilns. The stack gases exhausted from each such facilityis controlled by environmental regulations. Such regulations requireabatement of carbon monoxide (CO), carbon dioxide (CO₂), nitrogen oxide(NOx), sulfur oxide (SOx), as well as halogens, such as chloride andfluorides, and trace metals particularly, mercury, lead, and zinc.

Various methods and apparatus have been proposed for abating thesepollutants in stack gases. In particular, a variety of methods have beenproposed for reducing pollutants released from coal-fired stack gas. Onemethod of cleaning coal-fired stack gas is the use of scrubbers whichinject a liquid or slurry into a gas stream that washes variouspollutants, such as with acidic compounds, from the stack gas stream.Another type of cleaning is the use of an exhaust burner that combustsvolatile materials and other combustible compounds, reducing pollutionin the stack gas.

Specifically, it has been proposed that the stack gases be mixed withammonia or urea and then passed through a catalyst in which the ammoniareacts selectively with the nitrous oxides to form nitrogen gas in watervapor, or combustion of a sulfur-containing fossil fuel in the presenceof a calcium carbonate or magnesium carbonate to form calcium sulfate ormagnesium sulfate. See U.S. Pat. Nos. 8,181,451; 6,706,246; 5,525,317;5,237,939; 4,185,080; and 4,051,225. It has also been proposed to reducenitrogen in stack gas by passing the stack gas through a heat exchangehaving a SCR catalyst. See U.S. Pat. No. 5,918,555. Reduction of sulfuroxide content in stack gases has been proposed involving catalyzedoxidation to sulfur trioxide in the presence of an absorbent orcombusting sulfur-containing fuel in a combustion zone charged with aslurry in sulfuric acid solution. See U.S. Pat. Nos. 5,540,755;4,649,034; 4,284,015; and 4,185,080. Catalytically converting unburnedhydrocarbons and carbon monoxide to carbon dioxide and reducing nitrogenoxides to nitrogen subsequent to the combustion of fossil fuels whileabsorbing sulfur oxide has been proposed, where the catalytic materialis physically combined onto a dry powder of an adsorbent matrix selectfrom calcium aluminate, calcium aluminate cement, barium titanate, andcalcium titanate. See U.S. Pat. No. 4,483,259. It has also been proposedto pass the stack gases through a catalyst bed of a combination ofactive metals on the surface that is capable of reducing or convertingsulfur oxides, carbon monoxide and hydrocarbons to inert compounds suchas carbon dioxide, water and nitrogen. See U.S. Pat. No. 7,399,458.Levels of mercury in stack gases from coal combustion have also beenreduced by introducing a sorbent composition into the gas stream in azone where temperature is greater than 500° C. and where the sorbentcomposition comprises an effective amount of nitrate salt and/or anitrite salt. See U.S. Pat. Nos. 7,468,170 and 7,731,781.

Other types of cleaning stack gas have also been proposed and will beknown to those having skill in the art. These previous proposals have anumber of drawbacks. Many require addition of another gas or liquid suchas ammonia sulfuric acid, or the presence of an active metal catalyst.

One particular problem unresolved by current technology is carbongaseous pollutants that cannot be reduced by scrubbing, combustion, orcapture. It has been proposed to capture the carbon in the form ofcarbon dioxide, compress the carbon dioxide, and storing it in ageological formation. Zeolite has been proposed among others materialsto absorb carbon dioxide, and after sequestering the carbon dioxide,then regenerating the zeolite material. See “Carbon Dioxide CaptureUsing a Zeolite Molecular Sieve Sampling System for Isotopic Studies (¹³C and ¹⁴ C) of Respiration”, Radiocarbon, 47, 441-451 (2005); “AbsorbentMaterials for Carbon Dioxide Capture from Large Anthropogenic PointSources”, ChemSusChem 2009, 2, 796-854; “NIST Provides Octagonal Windowof Opportunity for Carbon Capture”, NIST Techbeat, Feb. 7, 2012.However, these methods involve the use of large particle sizes ofzeolite; for example, between 1/16 and ⅛ inch in size under conditionsto provide for adsorption of carbon dioxide and later regeneration. Assuch, these methods of absorbing carbon dioxide highlight the continuingproblem of disposing of the sequestered carbon dioxide.

There is therefore still a need for a method and apparatus toeffectively remove carbon monoxide, carbon dioxide, nitrous oxides,sulfur oxides and trace metals, such as mercury, from stack gaseswithout consuming expensive catalysts, without injecting additionalgases, liquids and/or solids into the stack gas, and without creatingwaste products that, themselves, present additional problems and cost indisposal. This is of particular concern in cleaning of stack gases coalfrom fire power plants because of the release of volatiles such as coaltar and other active pollutants along with carbon dioxide in the stackgas.

Presently disclosed is a method of cleaning stack gases comprising thesteps of:

-   -   (a) providing in a stack adapted to pass stack gases through a        first catalytic flow-through bed of calcium zeolite comprising        natural zeolite particles of a majority between 44 μm and 64 μm        in size at a temperature above the dew point between 125 and        500° F. and a pressure between 3 and 200 psi adapted to reduce        carbon oxides in the stack gases;    -   (b) providing in the stack adapted to pass stack gases        positioned adjacent the first catalytic flow-through bed, a        second catalytic flow-through bed of a blend between 25 and 75%        of sodium zeolite and calcium zeolite comprising natural sodium        and calcium zeolite particles of a majority between 65 μm and        125 μm in size at a temperature above the dew point between 125        and 500° F. and a pressure between 3 and 200 psi adapted to        reduce nitrogen oxides in the stack gases;    -   (c) providing in the stack adapted to pass stack gases        positioned adjacent the second catalytic flow-through bed, a        third catalytic flow-through bed of calcium zeolite comprising        natural zeolite particles of a majority between 78 μm and 204 μm        at a temperature above the dew point between 125 and 500° F. and        a pressure between 3 and 200 psi adapted to reduce sulfur oxides        in the stack gases; and    -   (d) passing stack gases selected from the group consisting of        volatiles from combustion of coal or from combustion of natural        gas or from a cement kiln sequential through the first catalytic        bed, the second catalytic bed, and the third catalytic bed each        collecting materials in the catalytic beds and providing gas        exiting the third catalytic bed with at least 70% reduction in        sulfur oxides, nitrogen oxides and carbon oxide.

The method where the stack gas is sequentially circulated through thefirst catalytic bed, the second catalytic bed, and the third catalyticbed may also involve removal from the stack gas of at least 50% or 70%of mercury in all forms.

Also presently disclosed is a method of cleaning stack gases comprisingthe steps of:

-   -   (a) providing in a stack adapted to pass stack gases through a        first catalytic flow-through bed of calcium zeolite comprising        natural zeolite particles of a majority between 44 μm and 64 μm        in size at a temperature above the dew point between 125 and        500° F. and a pressure between 3 and 200 psi adapted to reduce        carbon oxides in the stack gases;    -   (b) providing in the stack adapted to pass stack gases        positioned adjacent the first catalytic flow-through bed, a        second catalytic flow-through bed of a blend between 25 and 75%        of sodium zeolite and calcium zeolite comprising natural sodium        and calcium zeolite particles of a majority between 65 μm and        125 μm in size at a temperature above the dew point between 125        and 500° F. and a pressure between 3 and 200 psi adapted to        reduce nitrogen oxides in the stack gases;    -   (c) providing in the stack adapted to pass stack gases        positioned adjacent the second catalytic flow-through bed, a        third catalytic flow-through bed of calcium zeolite comprising        natural zeolite particles of a majority between 78 μm and 204 μm        at a temperature above the dew point between 125 and 500° F. and        a pressure between 3 and 200 psi adapted to reduce sulfur oxides        in the stack gases;    -   (d) passing stack gases selected from the group consisting of        volatiles from combustion of coal or from combustion of natural        gas or from a cement kiln sequential through the first catalytic        bed, the second catalytic bed, and the third catalytic bed each        collecting materials in the catalytic beds and providing gas        exiting the third catalytic bed with at least 70% reduction in        sulfur oxides, nitrogen oxides and carbon oxide; and    -   (e) purging solids and liquids from the first catalytic bed, the        second catalytic bed, and the third catalytic bed by        intermittently passing nitrogen through the beds to remove        solids and liquids collected from the stack gases by the beds.

Again, the method where the stack gas is sequentially circulated throughthe first catalytic bed, the second catalytic bed, and the thirdcatalytic bed may also involve removal from the stack gas of at least50% or 70% of mercury in all forms.

In any case, the method may also comprise in addition a fourth catalyticflow-through bed of calcium zeolite comprising natural zeolite particlesbetween 44 μm and 64 μm in size positioned in the stack before the firstcatalytic bed with an electrical charge on said fourth catalyticflow-through bed. This bed is to separately collect bauxite compoundsfrom the stack gases before passing through the first catalytic bed.

In any event, the method may also involve the gases exiting a stack fromthe third catalytic bed, whether or not a fourth catalytic flow-throughbed is used, with at least 90% or 95% reduction in bauxite compounds,sulfur oxides, nitrogen oxides, mercury oxide, and carbon oxide comparedto the stack gases delivered through the stack.

In any event, the method may involve where the stack gas is circulatedthrough the first catalytic bed, the second catalytic bed, and the thirdcatalytic bed, each positioned between screens of between 150 and 250mesh. In addition or alternatively, the first catalytic bed, the secondcatalytic bed, and the third catalytic bed may each be provided on amoving disk. The method may alternatively involve at least two series ofsequential circulations through the first catalytic bed, the secondcatalytic bed, and the third catalytic bed provided in parallel so thatthe stack gases can be cleaned by the method through one series of bedswhile other series of the beds can be cleaned as described below.

The method may alternatively be practiced separately to reduce carbonmonoxide and dioxide, sulfur oxides and/or nitrogen dioxides asdescribed in the claims set forth at the end of this application. Thisis particularly the case with stack gas from cement kilns and otherplants, which tend to focus on carbon dioxide.

Also disclosed is an alternative method of cleaning stack gasescomprising the steps of:

-   -   (a) providing in a stack adapted to pass stack gases of less        than 7% oxygen through a first catalytic flow-through bed of        calcium zeolite comprising natural zeolite particles at a        temperature above the dew point between 125 and 500° F. and a        pressure between 3 and 200 psi adapted to reduce carbon oxides        from the stack gases and increase oxygen levels in the stack        gas;    -   (b) providing in the stack adapted to pass stack gases        positioned adjacent the first catalytic flow-through bed, a        second catalytic flow-through bed of a blend between 25 and 75%        of sodium zeolite and calcium zeolite comprising natural sodium        and calcium zeolite particles at a temperature above the dew        point between 125 and 500° F. and a pressure between 3 and 200        psi adapted to reduce nitrogen oxides from the stack gases and        increase oxygen levels in the stack gas;    -   (c) providing in the stack adapted to pass stack gases        positioned adjacent the second catalytic flow-through bed, a        third catalytic flow-through bed of calcium zeolite comprising        natural zeolite particles at a temperature above the dew point        between 125 and 500° F. and a pressure between 3 and 200 psi        adapted to reduce sulfur oxides in the stack gases and increase        oxygen levels in the stack gas; and    -   (d) passing stack gases of less than 7% oxygen selected from the        group consisting of volatiles from combustion of coal or from        combustion of natural gas or from a cement kiln sequential        through the first catalytic bed, the second catalytic bed, and        the third catalytic bed each collecting materials catalytic beds        and providing gas exiting the third catalytic bed with at least        70% reduction in sulfur oxides, nitrogen oxides and carbon oxide        and greater than 15% oxygen.

In this alternative method, the beds providing the first catalytic bed,the second catalytic bed, and the third catalytic bed may also involvethe removal from the stack gas of at least 50% or 70% of mercury. Theoxygen exiting the third catalytic bed may be recirculated through theburners to provide fuel for the combustible system.

In any case, the alternative method may also comprise in addition afourth catalytic flow-through bed of calcium zeolite comprising naturalzeolite particles between 44 μm and 64 μm in size positioned in thestack before the first catalytic bed with an electrical charge on saidfourth catalytic flow-through bed to collect bauxite compounds from thestack gases before passing through the first catalytic bed.

In any event, the alternative method may also involve the gases exitinga stack from the third catalytic bed, whether or not a fourth catalyticflow is used, providing at least 90% or 95% reduction in bauxitecompounds, sulfur oxides, nitrogen oxides, mercury oxide, and carbonoxide compared to the stack gases delivered through the stack.

In any event, the alternative method may involve where the stack gas iscirculated through the first catalytic bed, the second catalytic bed,and the third catalytic bed, each positioned between screens of between150 and 250 mesh. In addition or alternatively, the first catalytic bed,the second catalytic bed, and the third catalytic bed may each beprovided on a moving disk. The method may alternatively involve at leasttwo series of sequential through the first catalytic bed, the secondcatalytic bed, and the third catalytic bed provided in parallel so stackgas can be cleaned by the method through one series of beds while otherseries of the beds can be purged as described below.

The alternative method may be practiced separately to reduce carbonmonoxide and dioxide, sulfur oxides and/or nitrogen dioxides asdescribed in the claims set forth at the end of this application.

Also disclosed is an apparatus for cleaning stack gases comprising:

-   -   (a) a first catalytic flow-through bed of natural calcium        zeolite with a porosity of a total surface area of not greater        than 1200 m²/g adapted to reduce sulfur oxides positioned in an        exhaust stack;    -   (b) a second catalytic flow-through bed of a blend of natural        sodium zeolite and natural calcium zeolite of a porosity with a        total surface area of not greater than 1200 m²/g adapted to        reduce nitrogen oxides positioned in the exhaust stack above the        first bed;    -   (c) a third catalytic flow-through bed of natural calcium        zeolite with a porosity of a total surface area not greater than        1200 m²/g adapted to reduce carbon oxides and mercury oxides        positioned in the exhaust stack above the second bed; and    -   (d) the exhaust stack adapted to provide a gas flow selected        from the group consisting of volatiles from combustion of coal        or combustion of natural gas sequential through the first        catalytic bed, the second catalytic bed, and the third catalytic        bed each collecting solids in the catalytic beds and providing        gas exiting the third catalytic bed with at least 70 or 90%        reduction in sulfur oxides, nitrogen oxides, and carbon oxide.

In the apparatus, the blend of natural sodium zeolite and naturalcalcium zeolite in the second catalytic bed may be between 25 and 75%.The apparatus having the first catalytic bed, the second catalytic bed,and the third catalytic bed may have provided between each bed on movingdisks. Further, the first catalytic bed, the second catalytic bed, andthe third catalytic bed may also have moving disks such that the stackgases in element (d) can be continually passed through the firstcatalytic bed, the second catalytic bed, and the third catalytic bed toprovide collection of solids and/or liquids while other portions or bedsof like compositions are purged with nitrogen to collect the solidsand/or liquids from the beds. The apparatus may also be provided in theaddition or in the alternative with first catalytic bed, secondcatalytic bed, and third catalytic bed adapted to be purged with gas orliquid nitrogen to collect the solids and/or liquids from the beds.

The apparatus may also be provided with a fourth catalytic flow-throughbed positioned in the exhaust gases before the first catalytic bed witha porosity of a total surface area not greater than 1200 m²/g adapted tocollect bauxite compounds before passage through the first catalyticbed. Alternatively, the first catalytic bed, the second catalytic bed,and the third catalytic bed each have a porosity of a total surface areanot greater than 800 m²/g and the fourth catalytic flow, if used, mayhave a porosity of a total surface area not greater than 800 m²/g.

In any event, the apparatus may also provide the gases exiting a stackfrom the third catalytic bed, whether or not a fourth catalytic flow isused, with at least 90% or 95% reduction in bauxite compounds, sulfuroxides, nitrogen oxides, mercury oxide, and carbon oxide compared to thestack gases delivered through the stack. In the case of cement kilns,the focus is on the reduction of carbon dioxide.

Also disclosed herein is a fertilizer product produced by the steps of:

-   -   (a) providing in a stack adapted to pass stack gases through a        first catalytic flow-through bed of calcium zeolite comprising        natural zeolite particles of a majority between 44 μm and 64 μm        in size at a temperature above the dew point between 125 and        500° F. and a pressure between 3 and 200 psi adapted to reduce        carbon oxides in the stack gases;    -   (b) providing in the stack adapted to pass stack gases        positioned adjacent the first catalytic flow-through bed, a        second catalytic flow-through bed of a blend between 25 and 75%        of sodium zeolite and calcium zeolite comprising natural sodium        and calcium zeolite particles of a majority between 65 μm and        125 μm in size at a temperature above the dew point between 125        and 500° F. and a pressure between 3 and 200 psi adapted to        reduce nitrogen oxides in the stack gases;    -   (c) providing in the stack adapted to pass stack gases        positioned adjacent the second catalytic flow-through bed, a        third catalytic flow-through bed of calcium zeolite comprising        natural zeolite particles of a majority between 78 μm and 204 μm        at a temperature above the dew point between 125 and 500° F. and        a pressure between 3 and 200 psi adapted to reduce sulfur oxides        in the stack gases;    -   (d) passing stack gases selected from the group consisting of        volatiles from combustion of coal or from combustion of natural        gas or from a cement kiln sequential through the first catalytic        bed, the second catalytic bed, and the third catalytic bed each        collecting materials in the catalytic beds and providing gas        exiting the third catalytic bed with at least 70% reduction in        sulfur oxides, nitrogen oxides and carbon oxide; and    -   (e) purging solids and liquids from the first catalytic bed, the        second catalytic bed, and the third catalytic bed by        intermittently passing nitrogen through the beds to remove        solids and liquids collected from the stack gases by the beds.

Alternatively disclosed herein is a fertilizer product produced by thesteps of:

-   -   (a) providing in a stack adapted to pass stack gases of less        than 7% oxygen through a first catalytic flow-through bed of        calcium zeolite comprising natural zeolite particles at a        temperature above the dew point between 125 and 500° F. and a        pressure between 3 and 200 psi adapted to reduce carbon oxides        from the stack gases and increase oxygen levels in the stack        gas;    -   (b) providing in the stack adapted to pass stack gases        positioned adjacent the first catalytic flow-through bed, a        second catalytic flow-through bed of a blend between 25 and 75%        of sodium zeolite and calcium zeolite comprising natural sodium        and calcium zeolite particles of at a temperature above the dew        point between 125 and 500° F. and a pressure between 3 and 200        psi adapted to reduce nitrogen oxides from the stack gases and        increase oxygen levels in the stack gas;    -   (c) providing in the stack adapted to pass stack gases        positioned adjacent the second catalytic flow-through bed, a        third catalytic flow-through bed of calcium zeolite comprising        natural zeolite particles at a temperature above the dew point        between 125 and 500° F. and a pressure between 3 and 200 psi        adapted to reduce sulfur oxides in the stack gases and increase        oxygen levels in the stack gas; and    -   (d) passing stack gases of less than 7% oxygen selected from the        group consisting of volatiles from combustion of coal or from        combustion of natural gas or from a cement kiln sequential        through the first catalytic bed, the second catalytic bed, and        the third catalytic bed each collecting materials in the        catalytic beds and providing gas exiting the third catalytic bed        with at least 70% reduction in sulfur oxides, nitrogen oxides        and carbon oxide and greater than 15% oxygen.

Also disclosed herein is a fertilizer product produced by the steps of:

-   -   (a) providing a first catalytic flow-through bed of natural        calcium zeolite with a porosity of a total surface area of not        greater than 1200 m²/g adapted to reduce sulfur oxides in a        stack gas;    -   (b) providing a second catalytic flow-through bed of a blend of        natural sodium zeolite and natural calcium zeolite with a        porosity of a total surface area of not greater than 1200 m²/g        adapted to reduce nitrogen oxides in a stack gas with the blend        of sodium zeolite and calcium zeolite between 25 and 75%;    -   (c) providing a third catalytic flow-through bed of natural        calcium zeolite with a porosity of a total surface area not        greater than 1200 m²/g adapted to reduce carbon oxides and        mercury oxides in a stack gas;    -   (d) passing stack gases selected from the group consisting of        volatiles from combustion of coal or combustion of natural gas        sequential through the first catalytic bed, the second catalytic        bed, and the third catalytic bed each collecting solids and        liquids in the catalytic beds and providing gas exiting the        third catalytic bed with at least 70% reduction in sulfur        oxides, nitrogen oxides, and carbon oxide; and    -   (e) purging the solids and liquids collected on the from the        first catalytic bed, the second catalytic bed, and the third        catalytic bed and collecting said solids and liquids purged from        the first catalytic bed, the second catalytic bed, and the third        catalytic bed to provide a fertilizer product.

In any case, the fertilizer product may be purged with gas or liquidnitrogen. The fertilizer product may be produced where the bedsproviding the first catalytic bed, the second catalytic bed, and thethird catalytic bed are each positioned between screens of between 150and 250 mesh. Alternatively, the fertilizer product may be produced withthe stack gas pasted through a fourth catalytic flow-through bed beforepassage through the first catalytic bed with a porosity of a totalsurface area not greater than 1200 m²/g adapted to collect bauxitecompounds before passage through the first catalytic bed.

In the fertilizer product, the gases exiting a stack from thirdcatalytic bed may be at least 90% or 95% reduction in sulfur oxides,nitrogen oxides, mercury oxide and carbon oxide from the stack gasesdelivered to the a first catalytic flow-through bed. In the alternative,the gases exiting the third catalytic bed may be at least 90% or even95% reduction in bauxite compounds, sulfur oxides, nitrogen oxides,mercury oxide, and carbon oxide from the stack gases where the stack gasis delivered to the beds through a fourth catalytic flow.

In the various embodiments of the method, apparatus or fertilizerproduct, the stack gas may include carbon monoxide (CO), carbon dioxide(CO₂), nitrous oxide (N0 _(X)), sulfur dioxide (SO₂) and nitrous dioxide(NO₂). The solid waste may also include nitrate salt formed by reactionof nitrogen and nitrogen compounds retained in the zeolet beds withavailable oxygen. And exit from the third catalytic bed will typicallyinclude excess oxygen from the reduction according in the first, secondand third catalytic beds, as described above. The apparatus may alsoinclude product purged with liquid nitrogen.

In any case, the exiting stack gas with increased oxygen levels may bereturned from the gas cleaning system to the burner where it iscombusted with the coal or natural gas. The system may also include asolid waste draw for collecting the materials and drawing them away fromthe gas cleaning section.

Other details, objects and advantages of the present invention willbecome apparent from the description of the preferred embodimentsdescribed below in reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The following description is described of the accompanying drawings:

FIG. 1 is a schematic illustrating a coal-fired boiler for electricpower generation using stack gases that are cleaned and solid/liquidproducts recovered in accordance with the present invention;

FIG. 2A is an enlarged portion of part of the stack gas cleaning andrecovery system shown in FIG. 1 where three catalytic flow beds areutilized;

FIG. 2B is an enlarged portion of part of the stack gas cleaning andrecovery shown in FIG. 1 where four catalytic beds are utilized;

FIG. 3 is a cross-section taken along line 3-3 of FIG. 2A or FIG. 2B;

FIG. 4 is a schematic illustrating a test facility designed to test thecleaning of stack gases and recovery of solids and liquids with theinvention;

FIG. 5 is an enlarged portion of the test facility shown in FIG. 4;

FIG. 6 is an illustration corresponding to FIG. 5 in top view showingthe movement of catalytic flow through three catalytic beds in FIG. 5;

FIG. 7A is a graph illustrating CO₂ before and after cleaning;

FIG. 7B is a graph illustrating SO₂ before and after cleaning; and

FIG. 7C is a graph illustrating NO before and after cleaning.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring to FIG. 1, schematic illustrating a coal-fired boiler forelectric power generation producing stack gases that are cleaned andsolid/liquid products recovered. A coal fired boiler 10 is shownutilizing the stack gas cleaning and recovery apparatus and method ofthe present invention. Fresh air intake 12 flows through preheater 14 tosupply preheated fresh air to the boiler 10 that is coal fired. Thestack gases 16 from boiler 10 pass through preheater 14 whereby heat istransferred to the fresh air intake 12.

The stack gases 16, now processed by preheater 14, are conveyed to anemission control unit where the stack gases 16 are circulated toemission control system 18 through inlet 20 and allowed to rise throughthe emission control system 18 and up through gas cleaning apparatus 22.The stack gases 16 at this point typically include carbon monoxide,carbon dioxide, nitrogen oxides and sulphur oxides. The stack gases 16also include water and particulates, such as aluminum oxides, mercurycompounds and other particulate matters, such as uranium and rare earthmetals, as well as halogens, such as fluoride and chloride.

With reference to FIGS. 2A-B, gas cleaning apparatus 22 may comprisefirst catalytic flow-through bed 24, second catalytic bed 26 and thirdcatalytic flow-through bed 28 as shown in FIG. 2A or through firstcatalytic flow-through bed 24, second catalytic flow-through bed 26,third catalytic flow-through bed 28 and fourth catalytic flow-throughbed 30 as shown in FIG. 2B. In FIG. 2A, the rising stack gases 16 incleaning apparatus 22 first flow through the first catalyticflow-through bed 24 followed by the adjacent second catalyticflow-through bed 26, and then followed by the third catalyticflow-through bed 28. When fourth catalytic flow-through bed 30 isutilized as shown in FIG. 2B, fourth catalytic flow-through bed 30 instack 32 in gas stack 16 ahead and adjacent the first catalyticflow-through bed 24.

First catalytic flow through bed 24 is calcium zeolite comprised ofnatural zeolite particles with a majority between 44 μm and 64 μm insize. By a “majority” in the particle size range means here, as well inthis application, that is highest in like particle size increments andthat it necessarily is not 50% of the particle sizes in the zeolite ofthe bed. The calcium zeolite is a calcium-sodium-potassiumaluminosilicate that is relative high calcium oxide that is availablefrom a natural source. Typical chemical analyses of such calcium zeoliteare (i) 2.85% calcium oxide (CaO), 2.85% potassium oxide (K₂O), 0.98%manganese oxide (MgO), 0.06% manganese oxide (MnO), 0.19% titaniumdioxide (TiO₂), 0.05% potassium oxide (P₂0₅), 0.03% sodium oxide (Na₂O),11.43% aluminum oxide (Al₂O₃), 1.26% ferric oxide (Fe₂O₃) 66.35% silicondioxide (SiO₂) and 13.28% LOI; and (ii) 3.4% calcium oxide (CaO), 3.0%potassium oxide (K₂O), 1.5% manganese oxide (MgO), 0.05% potassium oxide(P₂0₅), 0.3% sodium oxide (Na₂O), 12.1% aluminum oxide (Al₂O₃), 1.6%ferric oxide (Fe₂O₃), 70.0% silicon dioxide (SiO₂). A source for calciumzeolite, amongst others, is St. Cloud Mining Company mines at Winstonand Truth or Consequences, New Mexico 87901, or a similar mine availablein other parts of the world. By natural zeolite here and elsewhere inthis description refers to that which is mined as opposed to artificialcreated.

The depth and breadth of the first bed 24 is determined by the flow rateof the stack gases 16 and desired pressure drop, and the physicaldimensions of the stack 32 through which stack gases 16 are conveyed atthe gas cleaning apparatus 22. First catalytic flow-through bed 24 isprovided as a flow through bed held in position by lower screen 34 andupper screen 36 each of between 150 and 250 mesh designed to hold thebed of calcium zeolite in position while allowing flow through of thestack gases 16.

The primary function of first catalytic flow-through bed 24 is tosplitting carbon monoxide and carbon dioxide retaining the carbon in thezeolite bed. First catalytic flow-through bed 24 also captures ash andother particular matter as well as bauxite compound if the fourthcatalytic flow-through bed 30 is not provided as shown in FIG. 2A.

The stack gases 16 in cleaning apparatus 22 then flow through secondcatalytic flow-through bed 26 positioned adjacent first catalyticflow-through bed 24. Second catalytic flow-through bed 26 is comprisedof a blend between 25 and 75% of sodium zeolite and calcium zeolite witha majority of the natural sodium and calcium zeolite particles between65 μm and 125 μm in size available from a natural source. The source ofthe calcium zeolite can be the same as that used to provide firstcatalytic flow-through bed 24, but with a majority particle size between65 μm and 125 μm. The sodium zeolite may be natural sodium-potassiumclinoptilolite that is relative high sodium oxide. Typical chemicalanalyses of such sodium zeolite are (i) 3.5% sodium oxide (Na₂O), 3.8%potassium oxide (K₂O), 11.9% aluminum oxide (Al₂O₃), 0.7% ferric oxide(Fe₂O₃), 0.8% calcium oxide (CaO), 0.4% manganese oxide (MgO), 0.02%manganese oxide (MnO), 0.1% titanium oxide (TiO₂) and 69.1% silicondioxide (SiO₂), and (ii) 3.03% sodium oxide (Na₂O), 3.59% potassiumoxide (K₂O), 10.27% aluminum oxide (Al₂O₃), 0.86% ferric oxide (Fe₂O₃),1.77% calcium oxide (CaO), 0.00% potassium oxide (K₂O), 0.4% manganeseoxide (MgO), 0.02% manganese oxide (MnO), 0.11% titanium oxide (TiO₂),69.1% silicon dioxide (SiO₂), and 13.09% LOI. A source of the sodiumzeolite, amongst others, is the St. Cloud mines in Ash Meadows, Nev., ora similar mine in other parts of the world. Again, the size and depth ofthe second set of the flow though bed is determined by the physicaldimensions of the stack 32 and the flow rate and pressure drop throughthe stack 32 at the gas cleaning apparatus 22.

The primary purpose of the second flow through bed 26 is to capture andsplit nitrogen oxides (NOx) in the stack gas 16. The second catalyticflow through bed 26 is also effective in reduce water and metalcompounds such as mercury, lead, uranium and other trace materials.Again, a lower screen 38 and an upper screen 40 may be provided withmesh sizes between 150 and 250 mesh to maintain the second catalyticflow-through bed 28 while allowing appropriate flow through of stack gas16.

On exiting the second catalytic flow-through bed 26, the stack gases 16flow through the adjacent third catalytic flow-through bed 28. The thirdcatalytic flow-through bed is comprised of calcium zeolite similar inchemical analysis to the first catalytic flow-through bed 24 with amajority of natural zeolite particles size between 78 μm and 204.

The third catalytic flow-through bed 28 is primarily to split sulfuroxides present in the stack gas 16. The third catalytic flow through bedmay also reduces sulfur acids, calcium compounds and ash in the stackgas 16. The composition of natural calcium zeolite in third catalyticflow through bed 28 may be of the same composition as the firstcatalytic flow through bed 24, but with different zeolite particle sizeas described. Again, a lower screen 42 and an upper screen 44 is withmesh size between 150 and 250 mesh is provided to maintain the thirdcatalytic flow through bed 28.

Thus, a disclosed FIG. 2A is a method of cleaning stack gases comprisingthe steps of:

-   -   (a) providing in a stack adapted to pass stack gases through a        first catalytic flow-through bed 24 of calcium zeolite        comprising natural zeolite particles of a majority between 44 μm        and 64 μm in size at a temperature above the dew point between        125 and 500° F. and a pressure between 3 and 200 psi adapted to        reduce carbon oxides from the stack gases;    -   (b) providing in the stack adapted to pass stack gases        positioned adjacent the first catalytic flow-through bed 24, a        second catalytic flow-through bed 26 of a blend between 25 and        75% of sodium zeolite and calcium zeolite comprising natural        zeolite particles of a majority between 65 μm and 125 μm in size        at a temperature above the dew point between 125 and 500° F. and        a pressure between 3 and 200 psi adapted to reduce nitrogen        oxides in the stack gases;    -   (c) providing in the stack adapted to pass stack gases        positioned adjacent the second catalytic flow-through bed 26, a        third catalytic flow-through bed 28 of calcium zeolite        comprising natural zeolite particles of a majority between 78 μm        and 204 μm at a temperature above the dew point between 125 and        500° F. and a pressure between 3 and 200 psi adapted to reduce        sulfur oxides in the stack gases; and    -   (d) passing stack gases selected from the group consisting of        volatiles from combustion of coal or from combustion of natural        gas or from a cement kiln sequential through the first catalytic        bed 24, the second catalytic bed 26, and the third catalytic bed        28 each collecting solids in the catalytic beds and providing        gas exiting the third catalytic bed with at least 70% reduction        in sulfur oxides, nitrogen oxides and carbon oxide.

The method may also sequentially circulate through the first catalyticbed 24, the second catalytic bed 26, and the third catalytic bed 28 mayalso involve removal from the stack gas at least 50% or 70% of mercuryin all forms, namely, elemental and oxidized forms.

Alternatively disclosed in FIG. 2A is a method of cleaning stack gasescomprising the steps of:

-   -   (a) providing in a stack adapted to pass stack gases of less        than 7% oxygen through a first catalytic flow-through bed 24 of        calcium zeolite comprising natural zeolite particles at a        temperature above the dew point between 125 and 500° F. and a        pressure between 3 and 200 psi adapted to reduce carbon oxides        from the stack gases and increase oxygen levels in the stack        gas;    -   (b) providing in the stack adapted to pass stack gases        positioned adjacent the first catalytic flow-through bed 24, a        second catalytic flow-through bed 26 of a blend between 25 and        75% of sodium zeolite and calcium zeolite comprising natural        zeolite particles of a at a temperature above the dew point        between 125 and 500° F. and a pressure between 3 and 200 psi        adapted to reduce nitrogen oxides from the stack gases and        increase oxygen levels in the stack gas;    -   (c) providing in the stack adapted to pass stack gas positioned        adjacent the second catalytic flow-through bed 26, a third        catalytic flow-through bed 28 of calcium zeolite comprising        natural zeolite particles at a temperature above the dew point        between 125 and 500° F. and a pressure between 3 and 200 psi        adapted to reduce sulfur oxides in the stack gases and increase        oxygen levels in the stack gas; and    -   (d) passing stack gases of less than 7% oxygen selected from the        group consisting of volatiles from combustion of coal or from        combustion of natural gas or from a cement kiln sequential        through the first catalytic bed 24, the second catalytic bed 26,        and the third catalytic bed 28 each collecting solids in the        catalytic beds and providing gas exiting the third catalytic bed        with at least 70% reduction in sulfur oxides, nitrogen oxides        and carbon oxide and greater than 15% oxygen.

The invention is operative as evidenced by substantial increase inoxygen exiting the third catalytic bed 28 compared to the oxygen levelsin the stack gas entering the first catalytic bed 24. The paper byYoshitaka Toda et al. titled “Activation And Splitting of Carbon Dioxideon The Surface Of An Inorganic Electrode Material” (Published 31 Jul.2013) suggests a potential mechanism, namely, splitting off oxygen fromCO₂ leaving CO to be then reduced. One mechanism to accomplish CO₂splitting is electrophoresis disassociation of oxygen in the presence ofthe zeolite catalyst bed into various forms of carbon and oxygen,including oxygen radicals, such as the superoxide O₂— anion. Metalclusters formed in the process in the presence of the zeolite catalystmay also provide additional catalytic activity resulting in CO₂splitting.

Also, the nitrogen from the stack gas is in large part retained in thezeolite beds and is available for reaction with available oxygen presentparticularly during purging as described below.

Where a fourth catalytic flow through bed 30 is provided as shown inFIG. 2B, the fourth catalytic flow-through bed is provided in the stackgas 16 adjacent the first catalytic flow-through bed 24. This providesthat the gas stream 16 may flow through the fourthcatalytic-flow-through bed 30 before flowing into the first catalyticflow-through bed 24. The composition of the fourth catalyticflow-through bed 30 is the same as the first catalytic flow-through bed,namely, comprised of calcium zeolite with a majority of the naturalzeolite particles between 44 μm and 64 μm in size. The fourth catalyticflow-through bed is maintained in position by lower screen 46 and upperscreen 48 with a mesh size between 150 and 250 while allowing flow ofstack gas 16 though the bed. An electrical charge is also provided onthe lower screen 46 to provide that the fourth catalytic flow-throughbed 30 attracts and retains bauxite particles from stack gas 16. As aresult the fourth catalytic flow-through bed 30 of calcium zeolitecomprising natural zeolite particles between 44 μm and 64 μm in sizepositioned in the stack before the first catalytic bed 24 with anelectrical charge beneath said fourth catalytic flow-through bed 30 tocollect bauxite compounds from the stack gases before passing throughthe first catalytic bed.

Where the fourth catalytic flow-through catalytic bed 30 is provided asshown in FIG. 2B, aluminum oxide may be largely separately collected andseparately processed to recovered as explained below. The stack gas 16flowing through gas cleaning apparatus 22 is separately cleaned ofbauxite compounds as well as cleaned as described above of carbondioxide, carbon monoxide, nitrogen oxides, sulfur oxides as well asmercury oxides, water and other trace metals in the stack gas 16. Thecleaning of the stack gases 16 flow through first catalytic flow-throughbed 24, second catalytic flow-through bed 26, third catalyticflow-through bed 28, and if present fourth catalytic flow-through bed 30provides at least 90%, 95%, or even 99% reduction in bauxite compounds,sulfur oxides, nitrogen oxides, mercury oxides and carbon oxides fromthe stack gases 16.

FIGS. 7A-7C represent data taken from a combustion gas emissions testwhere charcoal and 3 g of organic sulfur were combusted in a combustionoven. During a first test run, data was collected from the lower fluestack before the stack gas 16 passed through the gas cleaning apparatus22. During a second test run, data was collected from the upper fluestack after the stack gas 16 passed through the gas cleaning apparatus.Data was collected every 5 seconds using a Testo 350XL portablecombustion multi-gas analyzer. Data for the first test run (lower fluestack) was compared to and plotted with data for the second test run(upper flue stack) to provide an analysis of the results of the gascleaning apparatus 22.

FIG. 7A illustrates measured levels of carbon dioxide (CO₂) (ppm) before(solid line) and after (dashed line) the stack gas 16 is cleaned by thecleaning apparatus 22.

FIG. 7B illustrates measured levels of sulfur dioxide (SO₂) (ppm) before(solid line) and after (dashed line) the stack gas 16 is cleaned by thecleaning apparatus 22.

FIG. 7C illustrates measured levels of nitrous oxide (NO) (ppm) before(solid line) and after (dashed line) the stack gas 16 is cleaned by thecleaning apparatus 22.

It was found by the comparison of the data that carbon dioxide in thestack gas 16 was reduced by at least 95% by the stack gas fromcoal-fired plant entering cleaning apparatus 22; sulfur dioxide in thestack gas 16 was reduced by at least 95% from the stack gas entering thecleaning apparatus 22; and nitrous oxide in the stack gas 16 was splitand reduced by 95% or more by the stack gas entering cleaning apparatus22. These results demonstrate the high effectiveness of the cleaningapparatus 22 in cleaning stack gas from a coal-fired power plant.

While the cleaning apparatus is in operation 22, material includingcarbon, sulfur, nitrogen, and other products are collected by thecatalytic through-flow beds. Intermittently, as appropriate, the firstcatalytic through-flow bed 24, second catalytic through-flow bed 26,third catalytic through-flow bed 28 and fourth catalytic through-flowbed 30 (where present) may be switched between parallel systems as shownin FIGS. 2 and 3. The stack gases 16 may, thus, continuing to flowthrough stack 32 and be cleaned in stack cleaning apparatus 22 while theparallel first catalytic through-flow bed 24, second catalyticthrough-flow bed 26, third catalytic through-flow bed 28 and fourthcatalytic through-flow bed 30 (where present) are rotated off line andpurged with nitrogen to remove material from the catalytic beds. Thispurging of the beds may be done with cryogenic nitrogen or nitrogen gas,or other suitable liquid or gas, generally referred to as a purge fluid.

During the purging process, purge fluid is released from a reservoir 54and the purging fluid passes through one or more of the first catalyticthrough-flow bed 24, second catalytic through-flow bed 26, thirdcatalytic through-flow bed 28 and fourth catalytic through-flow bed 30(where present). The purge fluid may be pressurized or may fall bygravity through one or more of the catalytic through-flow beds,releasing material from the catalytic through-flow beds.

This purging produces a solid waste largely of nitrate composition thatis discharged through outlet 50 into a container 52. The nitratecompounds can be formed by reaction of the nitrogen and nitrogencompounds retained by the zeolite beds with the oxygen present duringpurging. The mechanism of formation of these nitrate fertilizermaterials may involve catalytic splitting of the nitrogen compoundspresent in the stack gas stream into nitrogen retained in the zeolitebeds and/or the nitrogen compounds retained in the zeolite beds, whichare then available to react with free oxygen atoms and/or oxygenradicals in purging to form nitrate powders. Because large amounts ofnitrogen are present in the stack gas stream, relatively large amountsof nitrate compounds may be present in the fertilizers produced. Thesenitrate fertilizers provide a value byproduct of the present process.

If a fourth catalytic through-flow bed 30 is provided, that bed may beseparately purged through a separate outlet into a separate container(not shown) to allow for recovery of bauxite compounds as a separateproduct. Where a fourth catalytic bed 30 is not provided, the bauxitecompounds are collected in the first catalytic through-flow bed 24 andprovided as a part of a fertilizer composition and product. The metalssuch as mercury, zinc, lead and other trace metals are also collectedknown to be beneficial to soil is collected as part of the fertilizerproduct that is recovered.

The purging may also produce gases, such as oxygen (O₂) and nitrogen(N₂) that may be extracted by a first gas outlet 58 that transports aportion of the gases (e.g. N₂) to a recycler and a second gas outlet 60that transports a portion of the gases (e.g. O₂) to the burner forcombusting the fuel.

A test apparatus is illustrated in FIGS. 4-5. The testing apparatusincludes a stack 32 for transporting stack gas 16 to the gas cleaningapparatus 22 described above. The gas cleaning apparatus 22 is shown infurther detail in FIG. 5 and includes first 24, second 26 and third 28catalytic through-flow beds each having a zeolite composition asdescribed above. Each of the catalytic through-flow beds ay be connectedto a central drive shaft 58 that is adapted to rotate or otherwise moveeach of the catalytic through-flow beds, individually, from a firstposition where stack gas 16 passes through the bed to a second positionwhere the catalytic through-flow bed is purged by the purge fluid. Ahandle 60 is provided that may be translated vertically to select one ofthe catalytic through-flow beds and rotated or otherwise move theselected through-flow bed from the first position to the secondposition.

FIG. 6 is a top view of the cleaning apparatus 22 according to thetesting apparatus shown in FIGS. 4-5. In this view, the catalyticthrough-flow beds are aligned with the coal stack 32.

The tests with the test facility shown in FIGS. 4-6 included Kentuckyco-fired by propane, Ohio coal fired and two tests with charcoal mixedwith organic sulfur. The samples were fired by a propane burner at 62shown in FIG. 4 or in a combustion oven (not shown) before positioningbelow stack 32. These illustrate the operation of the method andequipment. The data from these tests is set forth in table and graphicform in the Appendix A to this application.

While the invention has been described with reference to certainembodiments, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted withoutdeparting from the scope of the invention. In addition, manymodifications may be made to adapt a particular situation or material tothe teachings of the invention without departing from its scope.Therefore, it is intended that the invention not be limited to theparticular embodiments disclosed, but that the invention will includeall embodiments falling within the scope of the appended claims.

What is claimed is:
 1. A method of cleaning stack gases comprising thesteps of: (a) providing in a stack adapted to pass stack gases through afirst catalytic flow-through bed of calcium zeolite comprising naturalzeolite particles of a majority between 44 μm and 64 μm in size at atemperature above the dew point between 125 and 500° F. and a pressurebetween 3 and 200 psi adapted to reduce carbon oxides in the stackgases; (b) providing in the stack adapted to pass stack gases positionedadjacent the first catalytic flow-through bed, a second catalyticflow-through bed of a blend between 25 and 75% of sodium zeolite andcalcium zeolite comprising natural sodium and calcium zeolite particlesof a majority between 65 μm and 125 μm in size at a temperature abovethe dew point between 125 and 500° F. and a pressure between 3 and 200psi adapted to reduce nitrogen oxides in the stack gases; (c) providingin the stack adapted to pass stack gases positioned adjacent the secondcatalytic flow-through bed, a third catalytic flow-through bed ofcalcium zeolite comprising natural zeolite particles of a majoritybetween 78 μm and 204 μm at a temperature above the dew point between125 and 500° F. and a pressure between 3 and 200 psi adapted to reducesulfur oxides in the stack gases; and (d) passing stack gases selectedfrom the group consisting of volatiles from combustion of coal or fromcombustion of natural gas or from a cement kiln sequential through thefirst catalytic bed, the second catalytic bed, and the third catalyticbed each collecting materials in the catalytic beds and providing gasexiting the third catalytic bed with at least 70% reduction in sulfuroxides, nitrogen oxides and carbon oxide.
 2. The method as set forth inclaim 1 where the beds providing the first catalytic bed, the secondcatalytic bed, and the third catalytic bed also remove from the stackgas at least 50% of mercury.
 3. The method as set forth in claim 1 wherethe beds providing the first catalytic bed, the second catalytic bed,and the third catalytic bed are each positioned between screens ofbetween 150 and 250 mesh.
 4. The method as set forth in claim 1 wherethe first catalytic bed, the second catalytic bed, and the thirdcatalytic bed are each provided on a moving disk.
 5. The method as setforth in claim 1 where at least two series of sequential through thefirst catalytic bed, the second catalytic bed, and the third catalyticbed are each provided in parallel so stack gas can be cleaned by themethod through one series of beds while other series of the beds can becleaned.
 6. The method as set forth in claim 1 comprising in addition afourth catalytic flow-through bed of calcium zeolite comprising naturalzeolite particles between 44 μm and 64 μm in size positioned in thestack before the first catalytic bed with an electrical charge on saidfourth catalytic flow-through bed to collect bauxite compounds from thestack gases before passing through the first catalytic bed.
 7. Themethod as set forth in claim 1 where the stack gases exiting from thirdcatalytic bed through the stack have at least 95% reduction in sulfuroxides, nitrogen oxides, and carbon oxide compared to the stack gasesdelivered to the first catalytic flow-through bed.
 8. The method as setforth in claim 6 where the stack gases exiting a stack from the thirdcatalytic bed through the stack is at least 95% reduction in bauxitecompound, sulfur oxides, nitrogen oxides, and carbon oxide compared tothe stack gases delivered through the stack to the a fourth catalyticflow-through bed.
 9. A method of cleaning stack gases comprising thesteps of: (a) providing in a stack adapted to pass stack gases through afirst catalytic flow-through bed of calcium zeolite comprising naturalzeolite particles of a majority between 44 μm and 64 μm in size at atemperature above the dew point between 125 and 500° F. and a pressurebetween 3 and 200 psi adapted to reduce carbon oxides in the stackgases; (b) providing in the stack adapted to pass stack gases positionedadjacent the first catalytic flow-through bed, a second catalyticflow-through bed of a blend between 25 and 75% of sodium zeolite andcalcium zeolite comprising natural sodium and calcium zeolite particlesof a majority between 65 μm and 125 μm in size at a temperature abovethe dew point between 125 and 500° F. and a pressure between 3 and 200psi adapted to reduce nitrogen oxides in the stack gases; (c) providingin the stack adapted to pass stack gases positioned adjacent the secondcatalytic flow-through bed, a third catalytic flow-through bed ofcalcium zeolite comprising natural zeolite particles of a majoritybetween 78 μm and 204 μm at a temperature above the dew point between125 and 500° F. and a pressure between 3 and 200 psi adapted to reducesulfur oxides in the stack gases; (d) passing stack gases selected fromthe group consisting of volatiles from combustion of coal or fromcombustion of natural gas or from a cement kiln sequential through thefirst catalytic bed, the second catalytic bed, and the third catalyticbed each collecting materials in the catalytic beds and providing gasexiting the third catalytic bed with at least 70% reduction in sulfuroxides, nitrogen oxides and carbon oxide; and (e) purging solids andliquids from the first catalytic bed, the second catalytic bed, and thethird catalytic bed by intermittently passing nitrogen through the bedsto remove solids and liquids collected from the stack gases by the beds.10. The method as set forth in claim 9 where the beds providing thefirst catalytic bed, the second catalytic bed, and the third catalyticbed also remove from the stack gas at least 50% of mercury.
 11. Themethod as set forth in claim 9 where the beds providing the firstcatalytic bed, the second catalytic bed, and the third catalytic bed areeach positioned between screens of between 150 and 350 mesh.
 12. Themethod as set forth in claim 9 where first catalytic bed, secondcatalytic bed, and third catalytic bed are purged with liquid nitrogento remove the solids and liquids from collected from stack gas by thebeds.
 13. The method as set forth in claim 9 where the first catalyticbed, the second catalytic bed, and the third catalytic bed are eachprovided on a moving disk.
 14. The method as set forth in claim 9 wherethe first catalytic bed, the second catalytic bed, and the thirdcatalytic bed are each provided on a moving disk such that the stackgases in step (d) can be continuously passed through the first catalyticbed, the second catalytic bed, and the third catalytic bed to providecollection of solids and/or liquids from the stack gases while otherportions of the same bed or like beds are purged with nitrogen to removethe solids and liquids from the stack gas by the beds.
 15. The method asset forth in claim 9 where at least two series of sequential through thefirst catalytic bed, the second catalytic bed, and the third catalyticbed are provided in parallel so stack gas can be cleaned by the methodthrough one series of beds while other series of the beds can becleaned.
 16. The method as set forth in claim 11 where first catalyticbed, second catalytic bed, and third catalytic bed are purged withliquid nitrogen to remove the solids and liquids from collected fromstack gas by the beds.
 17. The method as set forth in claim 9 comprisingin addition a fourth catalytic flow-through bed of calcium zeolitecomprising natural zeolite particles between 44 μm and 64 μm in sizepositioned in the stack before the first catalytic bed with anelectrical charge beneath said fourth catalytic flow-through bed tocollect bauxite compounds from the stack gases before passing throughthe first catalytic bed.
 18. The method as set forth in claim 9 wherethe fourth catalytic flow-through bed is on a rotating disk so the stackgases are continuously move through the fourth bed while other portionsof the same beds or a like bed are purged with nitrogen to remove solidsand liquids collected from the stack gas by the fourth bed.
 19. Themethod as set forth in claim 18 where the nitrogen is liquid nitrogen.20. The method as set forth in claim 9 where the beds providing thefirst catalytic bed, the second catalytic bed, and the third catalyticbed also remove from the stack gas at least 90% of mercury.
 21. Themethod as set forth in claim 9 where the stack gases exiting from thirdcatalytic bed through the stack have at least 95% reduction in sulfuroxides, nitrogen oxides, and carbon oxide compared to the stack gasesdelivered to the a first catalytic flow-through bed.
 22. The method asset forth in claim 9 where the beds providing the first catalytic bed,the second catalytic bed, and the third catalytic bed also remove fromthe stack gas at least 70% of mercury.
 23. The method as set forth inclaim 17 where the stack gases exiting from third catalytic bed throughthe stack have at least 95% reduction in bauxite compounds, sulfuroxides, nitrogen oxides, and carbon oxide compared to the stack gasesdelivered through the stack to the fourth catalytic flow-through bed.24. A method of cleaning stack gases comprising the steps of: (a)providing in a stack adapted to pass stack gases of less than 7% oxygenthrough a first catalytic flow-through bed of calcium zeolite comprisingnatural zeolite particles at a temperature above the dew point between125 and 500° F. and a pressure between 3 and 200 psi adapted to reducecarbon oxides from the stack gases and increase oxygen levels in thestack gas; (b) providing in the stack adapted to pass stack gasespositioned adjacent the first catalytic flow-through bed, a secondcatalytic flow-through bed of a blend between 25 and 75% of sodiumzeolite and calcium zeolite comprising natural sodium and calciumzeolite particles at a temperature above the dew point between 125 and500° F. and a pressure between 3 and 200 psi adapted to reduce nitrogenoxides from the stack gases and increase oxygen levels in the stack gas;(c) providing in the stack adapted to pass stack gases positionedadjacent the second catalytic flow-through bed, a third catalyticflow-through bed of calcium zeolite comprising natural zeolite particlesat a temperature above the dew point between 125 and 500° F. and apressure between 3 and 200 psi adapted to reduce sulfur oxides in thestack gases and increase oxygen levels in the stack gas; and (d) passingstack gases of less than 7% oxygen selected from the group consisting ofvolatiles from combustion of coal or from combustion of natural gas orfrom a cement kiln sequential through the first catalytic bed, thesecond catalytic bed, and the third catalytic bed each collectingmaterials in the catalytic beds and providing gas exiting the thirdcatalytic bed with at least 70% reduction in sulfur oxides, nitrogenoxides and carbon oxide and greater than 15% oxygen.
 25. The method asset forth in claim 24 where the beds providing the first catalytic bed,the second catalytic bed, and the third catalytic bed are eachpositioned between screens of between 150 and 250 mesh.
 26. The methodas set forth in claim 24 where the first catalytic bed, the secondcatalytic bed, and the third catalytic bed are each provided on a movingdisk.
 27. The method as set forth in claim 24 where at least two seriesof sequential through the first catalytic bed, the second catalytic bed,and the third catalytic bed are each provided in parallel so stack gascan be cleaned by the method through one series of beds while otherseries of the beds can be cleaned.
 28. The method as set forth in claim24 comprising in addition a fourth catalytic flow-through bed of calciumzeolite comprising natural zeolite particles in the stack before thefirst catalytic bed with an electrical charge on said fourth catalyticflow-through bed to collect bauxite compounds from the stack gasesbefore passing through the first catalytic bed and increase oxygenlevels in the stack gas.
 29. The method as set forth in claim 24 wherethe stack gases exiting from third catalytic bed through the stack haveat least 95% reduction in sulfur oxides, nitrogen oxides, and carbonoxide compared to the stack gases delivered to the first catalyticflow-through bed.
 30. The method as set forth in claim 28 where thestack gases exiting a stack from the third catalytic bed through thestack is at least 95% reduction in bauxite compounds, sulfur oxides,nitrogen oxides, and carbon oxide compared to the stack gases deliveredthrough the stack to the a fourth catalytic flow-through bed.
 31. Amethod of cleaning stack gases comprising the steps of: (a) providing ina stack adapted to pass stack gases through a first catalyticflow-through bed of calcium zeolite comprising natural zeolite particlesat a temperature above the dew point between 125 and 500° F. and apressure between 3 and 200 psi adapted to reduce carbon oxides from thestack gases and increase oxygen levels in the stack gas; (b) providingin the stack adapted to pass stack gases positioned adjacent the firstcatalytic flow-through bed, a second catalytic flow-through bed of ablend between 25 and 75% of sodium zeolite and calcium zeolitecomprising natural sodium and calcium zeolite particles at a temperatureabove the dew point between 125 and 500° F. and a pressure between 3 and200 psi adapted to reduce nitrogen oxides from the stack gases andincrease oxygen levels in the stack gas; (c) providing in the stackadapted to pass stack gases positioned adjacent the second catalyticflow-through bed, a third catalytic flow-through bed of calcium zeolitecomprising natural zeolite particles at a temperature above the dewpoint between 125 and 500° F. and a pressure between 3 and 200 psiadapted to reduce sulfur oxides in the stack gases and increase oxygenlevels in the stack gas; (d) passing stack gases of less than 7% oxygenselected from the group consisting of volatiles from combustion of coalor from combustion of natural gas or from a cement kiln sequentialthrough the first catalytic bed, the second catalytic bed, and the thirdcatalytic bed each collecting solids in the catalytic beds and providinggas exiting the third catalytic bed with at least 70% reduction insulfur oxides, nitrogen oxides and carbon oxide and at least 15% oxygen;and (e) purging solids and liquids from the first catalytic bed, thesecond catalytic bed, and the third catalytic bed by intermittentlypassing nitrogen through the beds to remove solids and liquids collectedfrom the stack gases by the beds.
 32. The method as set forth in claim31 where the beds providing the first catalytic bed, the secondcatalytic bed, and the third catalytic bed are each positioned betweenscreens of between 150 and 350 mesh.
 33. The method as set forth inclaim 31 where first catalytic bed, second catalytic bed, and thirdcatalytic bed are purged with liquid nitrogen to remove the solids andliquids from collected from stack gas by the beds.
 34. The method as setforth in claim 31 where the first catalytic bed, the second catalyticbed, and the third catalytic bed are each provided on a moving disk. 35.The method as set forth in claim 31 where the first catalytic bed, thesecond catalytic bed, and the third catalytic bed are each provided on arotating disk such that the stack gases in step (d) can be continuouslypassed through the first catalytic bed, the second catalytic bed, andthe third catalytic bed to provide collection of solids and/or liquidsfrom the stack gases while other portions of the same bed or like bedsare purged with nitrogen to remove solids and liquids from the stack gasby the beds.
 36. The method as set forth in claim 31 where at least twoseries of sequential through the first catalytic bed, the secondcatalytic bed, and the third catalytic bed are provided in parallel sostack gas can be cleaned by the method through one series of beds whileother series of the beds can be cleaned.
 37. The method as set forth inclaim 31 where first catalytic bed, second catalytic bed, and thirdcatalytic bed are purged with liquid nitrogen to remove the solids andliquids from collected from stack gas by the beds.
 38. The method as setforth in claim 31 comprising in addition a fourth catalytic flow-throughbed of calcium zeolite comprising natural zeolite particles positionedin the stack before the first catalytic bed with an electrical charge onsaid fourth catalytic flow-through bed to collect bauxite compounds fromthe stack gases before passing through the first catalytic bed.
 39. Themethod as set forth in claim 31 where the fourth catalytic flow-throughbed is on a rotating disk so the stack gases are continuously movethrough the fourth bed while other portions of the same beds or a likebed are purged with nitrogen to remove solids and liquids collected fromthe stack gas by the fourth bed.
 40. The method as set forth in claim 39where the nitrogen is liquid nitrogen.
 41. The method as set forth inclaim 31 where the stack gases exiting from third catalytic bed throughthe stack have at least 95% reduction in sulfur oxides, nitrogen oxides,and carbon oxide compared to the stack gases delivered to the a firstcatalytic flow-through bed.
 42. The method as set forth in claim 38where the stack gases exiting from third catalytic bed through the stackhave at least 95% reduction in bauxite compounds, sulfur oxides,nitrogen oxides, and carbon oxide compared to the stack gases deliveredthrough the stack to the fourth catalytic flow-through bed.
 43. A methodof cleaning sulfur oxides stack gases comprising the steps of: (a)positioning a catalytic flow-through bed of natural calcium zeolite witha porosity of a total surface area of not greater than 1200 m²/g adaptedto reduce sulfur oxides in a stack gas; and (b) passing stack gasesselected from the group consisting of volatiles from combustion of coalor combustion of natural gas sequential through the catalytic bed withat least 90% reduction in sulfur oxides.
 44. The method as set forth inclaim 43 where the catalytic bed is positioned between screens each ofbetween 150 and 250 mesh.
 45. The method as set forth in claim 43 wherethe catalytic bed is provided on moving disks.
 46. The method as setforth in claim 43 where the catalytic bed is provided on a moving disksuch that the stack gases in step (a) can be continually passed throughthe catalytic bed to provide collection of solids and/or liquids whileother portions or beds are purged with nitrogen to collect the solidsand/or liquids from the beds.
 47. The method as set forth in claim 46where the catalytic bed is purged with liquid nitrogen to collect thesolids and/or liquids from the beds.
 48. The method as set forth inclaim 43 where in addition the stack gas is pasted through anothercatalytic flow-through bed before passing through the first catalyticbed with a porosity of a total surface area not greater than 1200 m²/gadapted to collect bauxite compounds before passage through the firstcatalytic bed.
 49. The method as set forth in claim 48 where the othercatalytic flow-through bed is on a moving disk so the stack gases arecontinuously moved through the other bed while another portion of thedisk is being purged with nitrogen.
 50. The method as set forth in claim43 where the catalytic bed have a porosity of a total surface area notgreater than 800 m²/g.
 51. The method as set forth in claim 48 where theother catalytic flow-through bed has a porosity of a total surface areanot greater than 800 m²/g.
 52. The method as set forth in claim 43 wherethe gases exiting a stack from catalytic bed has at least 95% reductionin sulfur oxide from the stack gases delivered to the other catalyticflow-through bed.
 53. Apparatus for cleaning stack gases comprising: (a)a first catalytic flow-through bed of natural calcium zeolite with aporosity of a total surface area of not greater than 1200 m²/g adaptedto reduce sulfur oxides positioned in an exhaust stack; (b) a secondcatalytic flow-through bed of a blend of natural sodium zeolite andnatural calcium zeolite of a porosity with a total surface area of notgreater than 1200 m²/g adapted to reduce nitrogen oxides positioned inthe exhaust stack above the first bed; (c) a third catalyticflow-through bed of natural calcium zeolite with a porosity of a totalsurface area not greater than 1200 m²/g adapted to reduce carbon oxidesand mercury oxides positioned in the exhaust stack above the second bed;and (d) the exhaust stack adapted to provide a gas flow selected fromthe group consisting of volatiles from combustion of coal or combustionof natural gas sequential through the first catalytic bed, the secondcatalytic bed, and the third catalytic bed each collecting solids in thecatalytic beds and providing gas exiting the third catalytic bed with atleast 90% reduction in sulfur oxides, nitrogen oxides, and carbon oxide.54. The apparatus as set forth in claim 53 where the beds providing thefirst catalytic bed, the second catalytic bed, and the third catalyticbed are each positioned between screens of between 150 and 250 mesh. 55.The apparatus as set forth in claim 53 where the blend of natural sodiumzeolite and natural calcium zeolite in the second catalytic bed isbetween 25 and 75%.
 56. The apparatus as set forth in claim 53 where thefirst catalytic bed, the second catalytic bed, and the third catalyticbed are each provided on moving disks.
 57. The apparatus as set forth inclaim 53 where the first catalytic bed, the second catalytic bed, andthe third catalytic bed are each provided on moving disks such that thestack gases in element (d) can be continually passed through the firstcatalytic bed, the second catalytic bed, and the third catalytic bed toprovide collection of solids and/or liquids while other portions or bedsof like compositions are purged with nitrogen to collect the solidsand/or liquids from the beds.
 58. The apparatus as set forth in claim 53where first catalytic bed, second catalytic bed, and third catalytic bedare adapted to be purged with liquid nitrogen to collect the solidsand/or liquids from the beds.
 59. The apparatus as set forth in claim 53where a fourth catalytic flow-through bed is provided in the exhaustbelow the first catalytic bed with a porosity of a total surface areanot greater than 1200 m²/g adapted to collect bauxite compounds beforepassage through the first catalytic bed.
 60. The apparatus as set forthin claim 59 where the fourth catalytic flow-through bed is a moving diskso the stack gases are continuously move there through while anotherportion of the disk is being purged with nitrogen.
 61. The apparatus asset forth in claim 60 where the nitrogen is liquid nitrogen.
 62. Theapparatus as set forth in claim 53 where the beds providing firstcatalytic bed, second catalytic bed, and third catalytic bed each have aporosity of a total surface area not greater than 800 m²/g.
 63. Theapparatus as set forth in claim 59 where the fourth catalyticflow-through bed has a porosity of a total surface area not greater than800 m²/g.
 64. The apparatus as set forth in claim 53 where the fourthcatalytic flow-through bed has a porosity of a total surface area notgreater than 800 m²/g.
 65. The apparatus as set forth in claim 53 wherethe exhaust is adapted to exit gases from third catalytic bed having atleast 95% reduction in sulfur oxides, nitrogen oxides, mercury oxide andcarbon oxide compared to the stack gases delivered to the a firstcatalytic flow-through bed.
 66. The apparatus as set forth in claim 59where the stack is adapted to exit gases from third catalytic bed withat least 95% reduction in bauxite compounds, sulfur oxides, nitrogenoxides, mercury oxides, and carbon oxide from the stack gases deliveredto the a fourth catalytic flow-through bed.
 67. An apparatus of cleaningsulfur oxides from stack gases comprising: (a) a stack adapted toprovide for exit of stack gases; (b) a catalytic flow-through bed ofnatural calcium zeolite with a porosity with a total surface area of notgreater than 1200 m²/g adapted to reduce sulfur oxides positioned in thestack; and (c) the stack adapted to provide for flow-through gasesselected from the group consisting of volatiles from combustion of coalor combustion of natural gas the catalytic bed to provide for at least90% reduction in sulfur oxides exiting from the stack compared to thesulfur oxide content in the stack gases delivered to the catalyticflow-through bed.
 68. The apparatus as set forth in claim 67 where thecatalytic bed is positioned between screens each of between 150 and 250mesh.
 69. The apparatus as set forth in claim 67 where the catalytic bedis provided on rotating disk.
 70. The apparatus as set forth in claim 67where the catalytic bed is provided on a rotating disk such that thestack gases in step (c) can be continually passed through the catalyticbed to provide collection of solids and/or liquids while other portionsor beds is purged with nitrogen to collect the solids and/or liquidsfrom the beds.
 71. The apparatus as set forth in claim 70 where thecatalytic bed is purged with liquid nitrogen to collect the solidsand/or liquids from the beds.
 72. The apparatus as set forth in claim 67where in addition positioned in the stack another catalytic flow-throughbed below the first catalytic bed with a porosity of a total surfacearea not greater than 1200 m²/g adapted to collect bauxite compoundsbefore passage through the first catalytic bed.
 73. The apparatus as setforth in claim 72 where the other catalytic flow-through bed is on amoviing disk so the stack gases continuously move through said other bedwhile another portion of the disk is being purged with nitrogen.
 74. Theapparatus in claim 67 where the catalytic bed have a porosity of a totalsurface area not greater than 800 m²/g.
 75. The apparatus as set forthin claim 72 where the other catalytic flow-through bed has a porosity ofa total surface area not greater than 800 m²/g.
 76. The apparatus methodas set forth in claim 67 where the gases exiting the stack fromcatalytic bed has at least 95% reduction in sulfur oxide compared to thestack gases delivered to the catalytic flow-through bed.
 77. Afertilizer product produced by the steps of: (a) providing in a stackadapted to pass stack gases through a first catalytic flow-through bedof calcium zeolite comprising natural zeolite particles of a majoritybetween 44 μm and 64 μm in size at a temperature above the dew pointbetween 125 and 500° F. and a pressure between 3 and 200 psi adapted toreduce carbon oxides in the stack gases; (b) providing in the stackadapted to pass stack gases positioned adjacent the first catalyticflow-through bed, a second catalytic flow-through bed of a blend between25 and 75% of sodium zeolite and calcium zeolite comprising naturalsodium and calcium zeolite particles of a majority between 65 μm and 125μm in size at a temperature above the dew point between 125 and 500° F.and a pressure between 3 and 200 psi adapted to reduce nitrogen oxidesin the stack gases; (c) providing in the stack adapted to pass stackgases positioned adjacent the second catalytic flow-through bed, a thirdcatalytic flow-through bed of calcium zeolite comprising natural zeoliteparticles of a majority between 78 μm and 204 μm at a temperature abovethe dew point between 125 and 500° F. and a pressure between 3 and 200psi adapted to reduce sulfur oxides in the stack gases; (d) passingstack gases selected from the group consisting of volatiles fromcombustion of coal or from combustion of natural gas or from a cementkiln sequential through the first catalytic bed, the second catalyticbed, and the third catalytic bed each collecting materials in thecatalytic beds and providing gas exiting the third catalytic bed with atleast 70% reduction in sulfur oxides, nitrogen oxides and carbon oxide;and (e) purging solids and liquids from the first catalytic bed, thesecond catalytic bed, and the third catalytic bed by intermittentlypassing nitrogen through the beds to remove solids and liquids collectedfrom the stack gases by the beds.
 78. A fertilizer product produced bythe steps of: (a) providing in a stack adapted to pass stack gases ofless than 7% oxygen through a first catalytic flow-through bed ofcalcium zeolite comprising natural zeolite particles at a temperatureabove the dew point between 125 and 500° F. and a pressure between 3 and200 psi adapted to reduce carbon oxides from the stack gases andincrease oxygen levels in the stack gas; (b) providing in the stackadapted to pass stack gases positioned adjacent the first catalyticflow-through bed, a second catalytic flow-through bed of a blend between25 and 75% of sodium zeolite and calcium zeolite comprising naturalsodium and calcium zeolite particles of at a temperature above the dewpoint between 125 and 500° F. and a pressure between 3 and 200 psiadapted to reduce nitrogen oxides from the stack gases and increaseoxygen levels in the stack gas; (c) providing in the stack adapted topass stack gases positioned adjacent the second catalytic flow-throughbed, a third catalytic flow-through bed of calcium zeolite comprisingnatural zeolite particles at a temperature above the dew point between125 and 500° F. and a pressure between 3 and 200 psi adapted to reducesulfur oxides in the stack gases and increase oxygen levels in the stackgas; and (d) passing stack gases of less than 7% oxygen selected fromthe group consisting of volatiles from combustion of coal or fromcombustion of natural gas or from a cement kiln sequential through thefirst catalytic bed, the second catalytic bed, and the third catalyticbed each collecting materials in the catalytic beds and providing gasexiting the third catalytic bed with at least 70% reduction in sulfuroxides, nitrogen oxides and carbon oxide and greater than 15% oxygen.79. A fertilizer product produced by the steps of: (a) providing a firstcatalytic flow-through bed of natural calcium zeolite with a porosity ofa total surface area of not greater than 1200 m²/g adapted to reducesulfur oxides in a stack gas; (b) providing a second catalyticflow-through bed of a blend of natural sodium zeolite and naturalcalcium zeolite with a porosity of a total surface area not greater than1200 m²/g adapted to reduce nitrogen oxides in a stack gas and the blendof sodium zeolite and calcium zeolite is between 25 and 75%; (c)providing a third catalytic flow-through bed of natural calcium zeolitewith a porosity of a total surface area not greater than 1200 m²/gadapted to reduce carbon oxides and mercury oxides in a stack gas; (d)passing stack gases selected from the group consisting of volatiles fromcombustion of coal or combustion of natural gas sequential through thefirst catalytic bed, the second catalytic bed, and the third catalyticbed each collecting solids and liquids in the catalytic beds andproviding gas exiting the third catalytic bed with at least 90%reduction in sulfur oxides, nitrogen oxides, and carbon oxide; and (e)purging the solids and liquids collected from the first catalytic bed,the second catalytic bed, and the third catalytic bed and collectingsaid solids and liquids purged from the first catalytic bed, the secondcatalytic bed, and the third catalytic bed to provide a fertilizerproduct.
 80. The fertilizer product as set forth in claim 79 where thebeds providing the first catalytic bed, the second catalytic bed, andthe third catalytic bed are each positioned between screens of between150 and 250 mesh.
 81. The fertilizer product as set forth in claim 79where in addition the stack gas is pasted through a fourth catalyticflow-through bed before passage through the first catalytic bed with aporosity of a total surface area not greater than 1200 m²/g adapted tocollect bauxite compounds before passage through the first catalyticbed.
 82. The fertilizer product set forth in claim 79 where the fourthcatalytic flow-through bed is being purged with nitrogen.
 83. Thefertilizer product as set forth in claim 82 where the nitrogen is liquidnitrogen.
 84. The fertilizer product as set forth in claim 79 where thegases exiting a stack from third catalytic bed have at least 95%reduction in sulfur oxides, nitrogen oxides, mercury oxide and carbonoxide from the stack gases delivered to the a first catalyticflow-through bed.
 85. The fertilizer product as set forth in claim 81where the gases exiting the stack from third catalytic bed is at least95% reduction in bauxite compounds, sulfur oxides, nitrogen oxides,mercury oxides, and carbon oxide from the stack gases delivered to the afourth catalytic flow-through bed.